Fix buffer allocator to use SYCL 2020 interface

[timmiesmith]

Existing Sample Changes

Description

In SYCL 2020 the interface of buffer_allocator is changed to require a template parameter that is the type of data that will be stored in the allocation. This change updates the buffer example from Chapter 7 of the DPC++ book to use the new interface.

Fixes Issue#

External Dependencies

None

Type of change

Please delete options that are not relevant. Add a 'X' to the one that is applicable.

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ X ] Implement fixes for ONSAM Jiras -- Jira reported to a project other than ONSAM

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [ X ] Command Line
• [ ] oneapi-cli
• [ ] Visual Studio
• [ ] Eclipse IDE
• [ ] VSCode
• [ ] When compiling the compliler flag "-Wall -Wformat-security -Werror=format-security" was used